Transfer printing

ABSTRACT

A TEMPORARY SUPPORT FOR TRANSFER PRINTING, WHICH CONSISTS OF A MEMBER SELECTED FROM THE SHEET OF PAPER AND AN ALUMINUM FOIL COATED ON ONE OF ITS FACES WITH A TRANSFER COATING OF ETHYLCELLULOSE WHICH BEARS A PIGMENTED FILM OF A RESIN SELECTED FROM THE GROUP CONSISTING OF THE THERMOPLASTIC POLYAMIDE AND VINYL RESINS.

Umted States Patent 3,574,049 TRANSFER PRINTING Pierre Sander, Tourcoing, France, assignor to Trentesaux-Toulemonde, Tourcoing, France No Drawing. Filed Mar. 14, 1967, Ser. No. 623,045 Claims priority, application grance, Mar. 16, 1966,

3 9 Int. Cl. B32b 15720, 23/22, 29/00 U.S. Cl. 161220 6 Claims ABSTRACT OF THE DISCLOSURE This invention relates to transfer printing, especially on plastics materials.

A transfer printing process has already been proposed in which a design is fixed to a temporary support by means of an adhesive and in which, after being soaked in water this design is applied to a final support where it remains when the temporary support is removed.

It has also been proposed to print designs on a temporary support using water inks and then to transfer the said designs by bringing a final support, which has been previously moistened, into contact with them.

In another process it has been proposed to transfer designs by applying heat. In this process the coloring materials, for example, inks, penetrate into the body of a temporary support made of paper and sublime on heating to high temperatures to condense on the material which forms a final support.

In other processes, it has been proposed to replace the adhesives on the temporary support by waxes or soft resins, onto which the designs to be transferred are printed. Just as, when water transfers are used, a residue of adhesive often remains on the final support, so in these processes, the waxes and soft resins are often transferred at the same time as the design onto the article to be printed. The result is that the printed article has a greasy appearance which is not always desired and also that the fixing of the inks of the design is not certain. The resulting designs look dull and offer little resistance to destructive agents and to weathering.

Processes which make it possible to produce hot marking on numerous materials have been proposed, for example, the process known by the name of Roll Leaf in the United States and the process known under the name of Blocking Foil in Great Britain. Such processes have the disadvantage that they also fix a part of a film detached from the temporary support onto the final support of the print. The presence of such a piece of film, which is generally glossy and covers more than the entire trans ferred design, is not always desirable.

Particularly in the field of synthetic plastics, films on which designs in several colors are to be printed have to pass through machines provided with inking stations arranged around a cylinder and may, as a result of their inherent elasticity, have to be held on a relatively inextensible adhesive belt whilst passing through the machine.

While such devices keep the material to be printed steady, it is not possible to have large drying distances between the printing positions for the different colours and as a result it is necessary to work at very slow speeds. The resulting transfer is of poor quality, and often unsatisfactory. When dealing with prints on non-planar surfaces, for example the surfaces of moulded articles, the

"ice

multicolor prints have to be effected color by color. Such processes take a very long time.

The present invention overcomes the disadvantages of the proposed processes and makes it possible to print multi-color designs onto articles which have been hitherto di-fiicult to print on account of their shape, and/or their physicochemical or mechanical properties.

The present invention provides a transfer process for printing a design on a final support which comprises (a) printing a design onto a temporary support, (b) superimposing the temporary support and the final support, (0) applying heat and/or pressure to the superimposed structure formed in (b), and (d) separating the temporary support from the final support which retains the printed design, the afiinity of the material of the design for the temporary support being lower than its affinity for the final support.

Advantageously, when heat is applied in step (c) of the process of the invention, the superimposed structure is allowed to cool before the temporary support is separated from the final support. Pressure may be applied to the superimposed structure in step (c) by, for example, passing it between cylinder rollers, by calendcring or by pressing it between plates.

Preferably, the difference between the affinity of the material of the design for the temporary support and its affinity for the final support increases with increasing temperature.

The temporary support may comprise a coating, called a transfer coating, of a material for which the material of the design has an affinity lower than its afiinity for the final support, and preferably the difference between the two affinities also increases with increasing temperature. The designs transferred may be of any color or size. They may be printed on the temporary support by any known technique, for example, by rotogravure, offset or fiexographic printing.

.Designs may be printed on the front and the back of a final support which is in the form of a sheet by applying two temporary support sheets to the respective faces of the final support in the process of the invention. On final supports which are transparent, translucent or opalescent it is possible to obtain a front and a back print of one and the same object inverted, making it possible to achieve a depth effect.

The transfer process of the invention makes it possible to print final supports whose rigidity, or lack of rigidity, makes them unsuitable for passing through a normal printing machine. There is no relative movement between the temporary support and the final support whilst the transfer is being made.

In a particular form of the process of the present invention, the design may be transferred during the manufacture of the final support itself. This is the case when the final support is made from a plastisol. The plastisol is spread onto the previously printed temporary support and during the gelling of the plastisol the design is completely transferred to the final support. Thus, particularly for moulded articles, the transfer may be carried out by incorporating the temporary support, in the form of, for example, a label, in the mould itself before moulding.

Whether or not the temporary support comprises a transfer coating, a protective varnish may be applied to the temporary support, optionally only to certain parts of it, before the temporary support is printed with the design in step (a) of the process of the invention, the affinities of the protective varnish and the material of the design for the temporary support being similar and the affinities of the protective varnish and the material of the design for the final support being similar, so that the varnish is transferred to the final support to ether with the design during the transfer process.

Such a protective varnish may be, for example, a synthetic resin in emulsion form. The presence of a layer of protective varnish gives the transferred designs excellent resistance to abrasion, dissolution, weathering and other causes of destruction. The use of emulsions makes it possible to apply heavier coatings giving superior mechanical properties.

The inks of the designs should be adapted to the properties of the materials of the final supports. They should contain colorants which do not migrate into the final support, which have good fastness to light and which, when colors are to be superimposed, are transparent, so that the shades obtained after transfer are not changed because of the opacity of one or more of the constituent colourants. On the other hand, when transfer onto a transparent final support is desired, the transferred designs can be rendered opaque by printing a white ink as a last layer onto the designs carried by the temporary support, I

The process of the present invention is particularly suited to the transference of designs onto final supports of polyvinyl chloride of polypropylene or of polyethylene. In such cases, especially when vinyl resins are used as bases for the inks which form the desired designs, it is advantageous to use a temporary support comprising a transfer coating of ethyl cellulose, which is practically incompatible with said vinyl resins, The transfer coating may also comprise up to 10% by weight of octyl adipate to give the transfer coating sufiicient coherence to receive a multicolored design by the printing technique employed.

The support for the ethyl cellulose transfer coating is 30 preferably substantially dimensionally stable to heat. It may be, for example, a sheet of thick aluminum foil, or a sheet of non-porous paper, or a sheet of thin aluminum foil optionally backed with paper, with a cellulosic film or with a plastic film of, for example, polyethylene or polypropylene.

Generally the thickness of the ethyl cellulose transfer coating is such that from 0.5 to 5 gIIlS. of ethyl cellulose covers one square metre of the surface of the temporary support.

The inks which form the designs may have, for example, the following composition by weight:

Parts Colorant 12 Vinyl resin 6 Toluene 10 Methylethyl ketone 72 OCHa COCHs As colorants, those known by the name of Microlithe K are especially suitable. These are fine dispersions of pigments in thermoplastic resins, for example, vinyl resins, and absolutely transparent prints may be obtained using them. The pigments themselves are generally organic materials, for example, azo pigments obtained by coupling or condensation, anthraquinone colorants, perinones or perylenes, quinacridones, thioindigoid, dioxazines or phthalocyanines. French patent specification No. 1,079,- 477 described Microlithe K colorants containing one or more compounds of the formulae the particles of which are coated with Rhodopas AX: which is a copolymer of vinylchloride and vinylacetate.

When a metallic-looking design is required, however, it is possible to use fine dispersions of metals in vinyl resins, and when there is no need for transparency, mineral pigments may be used, for example, a titanium dioxide-based pigment imparts a white color.

The vinyl resins used in the composition of the inks are generally copolymers of vinylchloride and vinylacetate, for example, Vinylite VMCH and Vinylite VYHH commercially distributed by Union Carbide of New York, or the AFS resins of Farbenfabriken Bayer AG. Polyamides 5 may also be used such as for instance the resin Versamide The thickness of the film of design material formed on the ethyl cellulose transfer coating may vary between 90 and 900 microns.

The following examples illustrate the invention. Percentages are by weight unless otherwise stated.

EXAMPLE 1 A face of an aluminum sheet, thickness 6.5 microns, was coated with the following composition:

Percent Ethyl cellulose cps. viscosity) 10 Octyl adipate 1 0 95% ethyl alcohol 89 so that, after evaporation of the ethyl alcohol, a coating of 6 gms./sq. metre of ethyl cellulose remained.

The coated face was then printed with a design, by means of an inking roller using ink which has been prepared as follows:

12 parts of a dispersion of the colorant of the formula HaCO COCHa I in a copolymer prepared from 85% vinylchloride and 15% vinylacetate (a dispersion in which the average particle size was less than 0.5 micron) were mixed, with good stirring, with 5 parts of the aforesaid copolymer, 5 parts of Farbenfabriken Bayers Kunstharz AFS resin, 10 parts of toluene and 68 parts of methyl ethyl ketone.

After drying, an aluminum film having on one of its faces a design layer separated from the metallic surface by ethyl cellulose was obtained.

This printed temporary support was then superimposed on a sheet of polyvinyl chloride so that the design contacted the polyvinyl chloride surface. Using plates heated to about 80 C., pressure and heat were applied to the contacted surfaces and then the superimposed structure was allowed to cool. After cooling, the aluminum film 00 together with its transfer coating of ethyl cellulose was I 3H3 Yellow 70 peeled off leaving the design firmly transferred to the poly- I 3 I vinyl chloride sheet.

was printed on a olyvinyl chloride sheet using an ink which had been prepared by mixing 8 parts of a 40% dispersion of a compound of the formula CH: Cl

in the copolymer of vinyl chloride and vinyl acetate described in Example 1, together with 2 parts of a 45% dispersion of a compound of the formula or or co co \C:C/ l S S c1 01 in the aforesaid copolymer, parts of the aforesaid copolymer, 5 parts of Kunstharz AFS, parts of toluene and 68 parts of methyl ethyl ketone.

EXAMPLE 3 A temporary support prepared as in Exemple 1 was printed with a design using an ink of the composition,

Percent Aluminum Microlithe K (finely powdered aluminum coated with a copolymer of 85% vinyl chloride and vinyl acetate) l5 Vinylite VMCH resin 7 Toluene 10 Methyl ethyl ketone 68 followed by an ink of the composition Percent Microlithe K Blue and/or Yellow 12 Vinylite VMCH resin 6 Toluene l0 Methyl ethyl ketone 72 On completing the transfer process as in Example 1, a polyvinyl chloride sheet was obtained having a metalliccolored design on one face.

EXAMPLE 4 A temporary support prepared as in Example 1 was printed with a design using an ink of the composition,

Percent Microlithe K Yellow, Red or Blue 12 Vinylite VMCH resin 6 Toluene 10 Methyl ethyl ketone 72 followed by an ink of the composition,

Titanium dioxide l0 Rhodopas AX 10 Vinylite VMCH resin 6 Toluene l0 Methyl ethyl ketone 64 On completing the transfer process as described in Example I, only in this case using a transparent polyvinyl chloride sheet, a non-transparent colored design was transferred onto the transparent polyvinyl chloride sheet.

EXAMPLE 5 A face of an aluminum sheet, thickness 6.5 microns, was coated with the following composition:

Percent Ethyl cellulose (20 cps. viscosity) 10 Octyl adipate 1 ethyl alcohol 89 so that, after evaporation of the ethyl alcohol, a coating of 6 gms./sq. metre of ethyl cellulose remained.

The coated face was then printed with a design, by means of an inking roller using ink which had been prepared as follows:

20 parts of a 50% dispersion of the colorant of the formula in the polyamide resin known under the trade name Versamide 930 (a dispersion in which the average particle size was less than 0.5 micron) were mixed, with good stirring, with 10 parts of the aforesaid resin, 35 parts of n-octane and 35 parts of isopropyl alcohol.

After drying, an aluminum film having on one of its faces, a design layer separated from the metallic surface by ethyl cellulose was obtained.

This printed temporary support was superimposed on a sheet, or a cylinder or any object of polyethylene. After heating of the superimposed structure under gentle pressure, the aluminum foil together with its transfer coating of ethyl cellulose was peeled off leaving the design firmly transferred to the polyethylene.

I claim:

1. A temporary support for transfer printing, which consists of a member selected from a sheet of paper and an aluminum foil which member is coated on one of its faces with a transfer coating of ethylcellulose which bears a pigmented film of vinyl chloride polymers or copolymers.

2. A temporary support as claimed in claim 1, which consist of an aluminum sheet backed on one of its faces with paper, and bearing on the other face a coating of ethyl cellulose covered with a multicolored film consisting essentially of a copolymer of vinylchloride and vinylacetate.

3. A temporary support as claimed in claim 1, wherein the pigmented film is of polyvinylchloride.

4. A temporary support as claimed in claim 1, wherein the transfer coating comprises from 0.5 to 6 gms. of ethyl cellulose per square metre.

5. A temporary support as claimed in claim 1, wherein the transfer coating comprises from 0.5 to 6 gms. of ethyl cellulose per square metre and has been printed with a layer of a design of pigmented polyvinylchloride.

6. A temporary support as claimed in claim 5, wherein the design layer is transparent and has a thickness of 90 to 900 microns.

3,265,524 8/1966 Echeagaray 161220 3,298,850 1/1967 Reed 117-3.1 References Cited UNITED STATES PATENTS JOHN T. GOOLKASIAN, Primary Examiner 12/1961 Betham 161 268X 5 L. T. KENDELL, Assistant Examiner 5/1956 Matthews 117-3.1

6/1961 Shepherd 161249 7 CL 12/1961 Reese 161406 1173.1, 73, 127, 157; 156230, 234, 309; 161249,

4/1962 Jankowski 1173.1 268, 406, 413

11/1962 Avelar 117 -3.1 

